This paper describes the effects of soil non-homogeneity, the soil–structure interaction and the two-parameter elastic foundation model on the free vibration of Euler–Bernoulli beams. Non-homogeneity of the soil foundation is described by parabolic variations of the two-parameter elastic soil foundation while Poisson's ratio is assumed to remain constant. Hence, the soil–structure interaction is quantified using a relative ratio of beam and soil foundation properties. The equation of motion including the previous effects is derived and the fundamental frequency parameters are computed. The influence of the above parameters on the free-vibration characteristics of the beam is investigated. The results obtained from this analytical method for a simply supported beam were found to be in very good agreement with data from the literature.